At present, there is a CDMA (Code Division Multiplex Access) system or an OFDM (Orthogonal Frequency Division Multiplex)/OFDMA (Orthogonal Frequency Divisional Multiplex Access) system as a radio communication system.
Further, there is also a radio communication system combining the CDMA system and the OFDMA system, in which diffusion processing is performed by an input signal and then a subcarrier is allocated to the diffusion processed signal (see, for example, Patent Documents 1 to 4).
Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-176012.
    Patent Document 2: Japanese National Publication of International Application No. 2005-5379691.    Patent Document 3: Japanese Laid-Open Publication No. 2001-203664.    Patent Document 4: Japanese Laid-Open Publication No. 2001-156744.
However, in the dual communication service, for example a service such as two radio communication systems including the CDMA and OFDMA system, a terminal receiving the service may select one service which is preferred for reception from among two communication services. In this case, the terminal may measure reception state of two communication services. Therefore, the terminal may perform reception processing by two communication services independently and in parallel. As a result, the terminal consumes a large amount of power.
Further, in the dual communication service, there is a problem that how much a lot of user data is transmitted in allocated frequency region.